Portable motor-driven saw



Sept. 23, 1941. o. R. FRITZ PORTABLE MOTOR-DRIVEN SAW Filed oct. 15.193s @s mid 'vdpvs Fr'd'z INVLNTOQ L Ty.

'Patented Sept. 23, 1941'.

PoR'rABLE Moron-naiven saw Oswald Rudolf Fritz, Vienna, Germany,assignor to the firm Ural-Masehinen-Vertriebsgesellschaft m. b. H.,Vienna,Ge

man Application October 15, 1938, Serial No. 235,165 rn Germany oetoter2o, 1937 2 Claims.

'I'he invention relates to portable saws driven by internal combustionengines, as used for felling trees, cross cutting and similar purposes,and having a chain saw with guide therefor, and the invention concernsmore particularly the starting arrangement for the motor of suchmachines.

Various kinds of starting devices have been proposed for such machines,including ,crank starters, kick starters and others, one of the mostsimple starting devices which has been selected as an example todescribe the principle of the present invention comprising a drum whichis directly or indirectly connected to the crank shaft of theengine,'and on which is wound a chain or rope which is given a sharppull by hand to start the engine. Owing to the machine standing freewithout anchorage when the engine is iirst started, and its weight beinginsuilicient to resist the sudden pull on the starter, the machine isdrawn along more or less in the direction of the pull, or even ifsteadied by hand it is shifted from its position. The engine is alsoliable to stop while the machine is in operation so that it is necessaryto start the engine under these conditions, and this must be possiblewithout danger of the saw chain guide being bent, lthe latter being inthe saw cut and being the sole sup' port for the engine.

For these reasons according to the invention the starting device is sobuilt into the machine or arranged therein that the direction oi' theforce applied to the starting device for starting the engine is in theplane of the chain saw guide. or substantially so. Further, thedirection in which the motor runs and the position of the pull member ofthe starter is such that in starting the engine the machine is forceddownwards towards the ground so that it remains stationary therebyfacilitating the starting up, particularly in the case of big machines.

The invention is illustrated in the accompanying drawing showing aportable motor driven saw provided with a starting device of the kindabove referred to by way of example, and wherein Fig. l is a side viewof the machine,

Fig. 2 a plan view thereof; and

Fig. 3 an end view.

Referring to the drawing, the machine is provided with a built on guide-`I for the chain saw; 2 and 3 designate the points of reversal of thethe machine being provided'with -spikes 6 on which the machine stands.To start the engine the operator takes hold of the starting handle 4with his right hand, places the other hand on the `machine at 1 tosteady it and gives `the handle 4 a sharp pull in the direction P. Theturning moment resulting from the two opposed forces represented by thepulling force and supporting force acts on the ground and the spikes 8consequently dig into the ground sothaty the machine is held stationary.Owing to the direction of pull being in the plane of the guide there areno lateral turning moments which might bend the guide I in the event. ofan operator holding the handle 8 on said guide. Noris there any tendencyfor the guide to be bent when the engine is started up again afterstopping while in the sawing position, i. e. when the guide I is clampedin the kerf and carries the engine.

The guide is merely subjected to a pulling moment when starting theengine, this moment being taken up by the operator steadying the machineat 1 and by the other operator holding the handle 8, and the pull is'also counteracted by the friction produced by the engagement of theguide I in the kerf. Thus it is impossible for the guide I to be bent,even should the operator starting the engine fail to steady the machinewith one hand and u se both hands to the handle 4 with a view toapplying more power iory starting. l

The arrangement is preferably also such that the point at which theforce is applied in operating the starter is in the saw guide planeboundchain saw, and 4 designates the handle of the l engine starter. Pdesignates the direction in which the handle 4 is pulled to start theengine,

l this direction of pull being in the plane of the ed by a lineconnecting the points of reversal of the chain saw and the ground orsubstantially so.

What I claim, is:

1. A portable chain-saw construction comprising an endless chain-saw, aninternal combustion engine for actuating said chain-saw, said enginecomprising a starter, oblong supporting means for said engine, saidsupporting means serving also to support said chain-saw, the latterfollowing substantially the oblong contour of said supporting means,said starter comprising pulling means for starting the engine, saidpulling means being operative in substantially the same longitudinalplane as said supporting means and adapted to receive a longitudinallydirected pulling torce for starting the engine, whereby torsionalstrains on said oblong engine supporting.

means are prevented during the starting of the engine.

2. The device claimed in claim l, in which said engine is provided withground gripping means and said pulling means is disposed for operationbelow the longitudinal axis of the said oblong supporting means.

OSWALD RUDOLF FRITZ.

